Writing implements having motion sensors to transform the relative motion or location of the implement into electrical signals are generally known. These implements, sometimes referred to as virtual pens, are commonly used as an input for artistic endeavors, such as in creating designs or otherwise controlling a graphics tablet, or for entering text in software applications. Known motion sensors for these implements include roller balls, accelerometers, optical elements, and the like. For example, one known motion sensor for a virtual pen employs splitting and recombining light beams for an accurate comparison of the surface geometries and textures against a master reference, a technique known as interferometry. These writing implements can be used with lap top computers, palm top computers, personal digital assistants (PDAs), personal communicators such as cellular telephones, or the like.
To capture handwriting motion, virtual pen devices include a motion sensor to translate motion into an electrical signal. As the user writes, with or without leaving any indicia on the writing surface, the motion of the virtual pen is detected and converted into electrical signals and subsequently transmitted and stored electronically. Handwriting recognition software can be used to convert the detection signals into text, or the text may be stored directly.
Some input devices, such as a “mouse” or a “finger wheel,” incorporate a disc or sphere to facilitate scrolling of information on a display. Such discs or spheres tend to be relatively large, and are difficult to incorporate into small devices such as virtual pens. These devices also tend to experience decreasing performance, or even complete malfunction, due to build up of dirt and oils, which can be exacerbated by their mechanics.
What is needed is a motion detection system with increased flexibility and functionality.